Process of making glue



Patented Apr. 30, 1929.

ADAM ROCHE, O1 LYNN, MASSACHUSETTS, ASSIGNOR TO LITIO ADHESIVE l: PROD- UC'lS COHIANY, 0F LYNN, MASSACHUSETTS, .A CORPORATION OII' MASSACHU- BETTE.

raocnss or MAKING GLUE.

Io Drawing.

'This invention has for its object to produce a glue which, on drying and setting, is waterproof, While the ob ect of the invention is to provide a glue having this characteristic which is use 111 for a variety of purposes, nevertheless I have particularly in mind to produce a glue which is especially applicable for use in connection with gypsum in the manufacture of wall board or in stucco Work or in other kinds of work wherein gypsum is utilized. The raw material, which is employed in carrying out my process for the production of glue, is preferably chrome tanned leather, although of course it will be understood that leather of other tannages may be utilized if desired.

The process, briefly stated, consists in treating scraps or shavings of chrome tanned leather with baths of sulphuric acid of increasing'dilution, so that the final product, while slightly acid, still contains a small proportion of chrome oxide which tans the gelatin, as the glue dries, to render the glue insoluble in water.

In carrying out this process, one may proceed as follows: The chrome tanned leatheror leather scrap is immersed in a sufficient quantity of sulphuric acid of about 20 B. to cover it, and the mixture is stirred together and permitted to stand for a half an hour more or less according to'the size of the pieces of leather. The liquor is then drained oif, carrying with it a portion of the extracted chrome oxide and is retained for the initial treatment of the next batch of leather. The leather scrap is then immersed in a sulphuric acid solution of about 10 B. The leather is permitted to remain in this bath with stirring for half an hour more or less, whereupon the liquor is drained off with such chrome oxide as may pass off therewith; and then the scrap is treated with a sulphuric acid solution of about5B. After thoroughly stirring for half an hour more or less, the liquor is drawn oil as thoroughly as can be effected. In this state, the leather scrap or particles of leather retain their shape. Then a small quantit of cold water is added so as to just cover t e scrap, and the scrap with the con- Applicatlon filed October 11, 1922. Serial No. 583,882.

tained water is then heated in a hot-water bath .until the leather is entirely dissolved. A glue is thus roduced which is acid in re action and in w ich sufiicient chrome oxide is left, so that as the glue dries the gelatin is tanned thereby, thus making the glue insoluble in water as previously stated; Whereas the leather scrap contains originally, say, 2% to 5% of chrome oxide, the final glue contains about 5/10% chrome oxide.

A glue, produced as thus described, may be used as an adhesive for gluing wood, for pasting sheets of paper, boxboard, labels or the like, and may also be used as a size in the manufacture of certain papers or wall boards. In fact, it may be used for most of the purposes for which an ordinary glue is employed Where its acidity is not detrimental. It may be mixed with clay for the manufacture of fire bricks, or with wood pulp, sawdust, infusorial earth or other suitable filler in the manufacture of molded articles. It is especially adapted for use with gypsum in the manufacture of gypsum board or in stucco work. In the manufacture of gypsum board, the gypsum is mixed with the glue instead of with water, thereby forming a thicker paste which is more easily worked, and which is spread in a thick la er on a sheet of paper or paper board, and in some cases a surface layer of paper or board is laid thereon. The glue, the gypsum, which itself is a sulphate. The result is that the acid glue prevents the gypsum from setting too rapidly and at the same time forms a perfect adhesive for bonding the gypsum to the layer or layers of paper board, and renders the gypsum itself substantially waterproof.

What I claim is:

1. A process of making glue from chrometanned leather, which comprises extracting only a major ortion of the chrome compound from the leat 'er in-successive baths of dilute sulphuric acid of successively decreasing acidities, and then heating the extracted leather in water until it dissolves therein to form a waterproof glue containing a sub stantial amount of chrome oxide.

being acid, does not react with 2. A process of making glue from chromethen heating the extracted leather in water tanned leathercontaining 2% to 5% chrome until the leather dissolves in the water to oxide, which comprises extracting the leather form a Waterproof glue containing a substan- 1 at room temperature in successlve baths of tial amount of chrome oxide.

5 sulphuric acld of about 20 Baum, about In testimony whereof I have affixed my 10 Baum and 5 Baum, each extraction signature. being performed for about half an hour, and ADAM HOCH E. 

